1. Field of the Invention
This invention relates to orthopedic surgical tools, and more particularly, to a system and method for attaching a surgical tool, such as a patellar resection guide, to an osteotomy trial for use in total knee arthroplasty.
2. Description of Related Art Including Information Disclosed under 37 CFR 1.97 and 1.98.
The surgical techniques of total knee arthroplasty are well known in the art. The leading cause of clinical failure of total knee arthroplasty, or total knee revision, is patella problems such as pain and dysfunction of the patella femoral joint. Many patellar failures are related to patellar misalignment with the femoral and tibial replacement components and with the knee extensor mechanism. When the patella fails, it frequently cannot be satisfactorily resurfaced, leading to either removal of its components or a patellectomy. These procedures often result in a major compromise to the functioning of the knee.
Another factor in determining ultimate patellar tracking and prosthesis longevity is accurate placement of the patellar prosthesis in the knee. Its articulation with the femoral groove and femoral component is especially integral to the longevity and success of the prosthesis. In order to maintain an acceptable overall patellar thickness and depth in the femoral groove, appropriate bone removal is a necessity, as well as accurate alignment of the cut bone surface and the patellar component in the sagittal, coronal and transverse planes.
One method popularized as a way to increase patellar prosthesis longevity is lateral retinacular release. Lateral retinacular release is used to improve patella tracking when the prosthesis does not track properly after it has been surgically applied. However, several problems associated with lateral release are well known including increased post-operative hemarthrosis and hematoma. Extensive lateral release also increases the probability of a vascular necrosis due to the sacrifice of the patellar branch of the superior lateral geniculate artery.
For a review of the surgical considerations regarding preparation of the patellar component in total knee arthroplasty, refer to Patellar Component in Total Knee Arthroplasty, Kelly, Current Concepts in Primary and Revision Total Knee Arthroplasty, 1996, pages 153-158. Related articles describing the state of the art include the following references: Bone Scanning in the Assessment of Patellar Viability Following Knee Replacement, Wetzner, et al, Clinical Orthopedics and Related Research, Number 199, October 1985, pages 215-219; Technical Considerations in Total Knee Arthroplasty, Dorr and Boiardo, Clinical Orthopedics and Related Research, Number 205, April 1986, pages 5-11; The Patellofemoral Component of Total Knee Arthroplasty, Brick and Scott, Clinical Orthopedics and Related Research, Number 231, June 1988, pages 163-178; Patellofemoral Functional Results and Complications With the Posterior Stabilized Total Condylar Knee Prosthesis, Aglietti et al, The Journal of Arthroplasty, Vol. 3, No.1, March 1988, pages 17-25; Blood Supply to the Patella, Brick and Scott, The Journal of Arthroplasty, 1989 Supplement, pages S75-S79; Patellofemoral Complications Following Total Knee Arthroplasty, Ritter, et al, The Journal of Arthroplasty, Vol. 11, No. 4, 1996, pages 368-372; A Soft Tissue Closure to Minimize Lateral Patellar Subluxation Following Total Knee Arthroplasty, Shaw, American Journal of Knee Surgery, Apr. 1986, Vol. 1, No. 2; and Surgical Techniques and Instrumentation in Total Knee Arthroplasty, Surgery of the Knee, Insall, James, et al., 2.sup.nd ed, Vol. 2, Chapter 26, pages 767-772.
The success of surgical techniques in total knee arthroplasty and patellar longevity is also influenced by the tools available to the surgeon. Presently, suitable instrumentation systems and cutting guides for the tibial and femoral components are known in the art. For example, see Surgical Techniques and Instrumentation in Total Knee Arthroplasty, Supra, Chapter 26, pages 767-772. These systems and tools have improved surgeons' abilities to implant the components properly and have reduced failures due to improper tibial and femoral condyle component alignment.
There are no known prior art teachings, however, of methods or tools which take into consideration the position of the patella in relation to the femoral condyle at the time of initial patella osteotomy. These cuts are extremely crucial in making sure that the proper relationship of the patella to the femoral groove is maintained and the patellar prosthetic is correctly sited. Instead, most known methods and surgical tools for resection of the patella and resurfacing its posterior surface require extension of the knee and eversion of the patella from its anatomically correct position.
References which discuss subject matter related to patella resection include U.S. Pat. Nos. 5,542,947; 5,520,692; 5,380,332; 5,147,365; 5,129,908; 5,108,401; 5,021,055; and 4,633,862, incorporated herein by reference. Use of the alignment guides, clamps, and surgical saws disclosed in these prior art references for removal of the diseased patellar joint surface and for creating the interface for the patellar component are used with the knee extended, the patella everted, and the extensor and connecting tissue pulled away, so the posterior surface of the patella is exposed.
Although the aforementioned references disclose how a surgeon typically retracts, reshapes, and profiles the patella, these procedures limit a surgeon's ability to accurately align the patellar component in reference to either the femoral or tibial component. When the patella is everted to make the resurfacing cuts, accurate alignment of the patellar surface with the extensor mechanism and articulating surfaces is inordinately difficult.
An alternative method of patella resection and resurfacing is disclosed in related U.S. patent application Ser. No. 09/210,848 which permits patella osteotomy while the patella remains in a non-everted, anatomically correct position. Referring to FIGS. 12 and 13, examples of a femoral component 150 depicting anatomically correct positions of the patella 160 in relation to the femoral articulating surfaces are shown. In FIG. 12, the patella 160 is shown adjacent to the femoral condyles 152, 154, where it articulates with portions of the medial 152 and lateral 154 femoral condyles in the true femorotibial area when the knee is in full flexion. When the knee is in extension, the patella 160 articulates solely with the femoropatellar gliding surface 156 as shown in FIG. 13. When the knee is moved between flexion and extion, the patella follows the path of the femoral groove 158. The femoral groove 158 includes the central portion of gliding surface 156 and the space defined between medial and lateral condyles 152, 154.
As disclosed in related U.S. patent application Ser. No. 09/210,848, a tool is now available to surgeons for resurfacing the patella in situ. When mounted directly on a standard metal trial component, such as the femoral trial component of the Hollister-Waddell Total Knee Prosthesis System.TM., the in situ patellar alignment and cutting guide assists the surgeon in determining the medial/lateral tilt, the superior/inferior cut angle, and resurfacing depth while bringing the patella into an optimum stabilized position before the resectioning is performed. Although the disclosure states that the tool is readily adaptable for use with other total knee systems known in the art, the disclosure does not teach an economical, efficient and safe system or method for using the resection guide with multiple osteotomy trial designs. The present invention meets these needs.